Electrical servo system for a flight control surface, method of detecting sensor failure, and method for determining correct function of a movement related flight control surface sensor

1 . A control system for a flight control surface, comprising:

a flight control surface moveable with respect to a mounting portion;

an electric actuator configured to actuate the flight control surface;

a movement-related flight control surface sensor, which is configured to acquire a quantity related to a movement of the flight control surface;

a movement-related actuator sensor, which is configured to acquire a quantity related to a movement of the electric actuator; and

a controller configured to control according to a cascaded closed loop control, wherein the movement-related flight control surface sensor is used in an outer closed loop control for movement control of the flight control surface, and the movement-related actuator sensor is used in an inner closed loop control for movement control of the electric actuator.

2 . The electrical servo system of claim 1 , wherein:

the movement-related flight control surface sensor is used in a position control of the flight control surface, and

the movement-related actuator sensor is used in a speed control of the electric actuator.

3 . The electrical servo system of claim 1 , wherein the flight control surface is pivotable with respect to the mounting portion.

4 . The electrical servo system of claim 1 , wherein the electric actuator comprises a rotary electric machine.

5 . The electrical servo system of claim 1 , further comprising a transmission interposed between the electric actuator and the flight control surface.

6 . The electrical servo system of claim 1 , wherein the movement-related flight control surface sensor is configured to acquire a quantity related to movement of a most downstream portion of a drive path from the electric actuator to the flight control surface.

7 . The electrical servo system of claim 1 , wherein the electric actuator is coupled to the mounting portion.

8 . The electrical servo system of claim 7 , wherein the movement-related actuator sensor is configured to acquire a quantity related to movement of an output portion of the electric actuator.

9 . The electrical servo system of claim 1 , wherein the movement-related flight control surface sensor and the movement-related actuator sensor are provided for a single flight control surface.

10 . The electrical servo system of claim 1 , wherein the system is configured for use in an aerial vehicle.

11 . The electrical servo system of claim 1 , wherein

the movement-related flight control surface sensor is configured to acquire a quantity related to a position of the flight control surface, and

the movement-related actuator sensor is configured to acquire a quantity related to a position of the electric actuator.

12 . The electrical servo system of claim 1 , wherein the flight control surface is a surface that enables attitude control around at least one axis of an aerial vehicle.

13 . A method of detecting sensor failure in an aerial vehicle, the aerial vehicle comprising:

a flight control surface moveable with respect to a mounting portion;

an electric actuator configured to actuate the flight control surface;

a movement-related flight control surface sensor, which is configured to acquire a quantity related to a movement of the flight control surface; and

a movement-related actuator sensor, which is configured to acquire a quantity related to a movement of the electric actuator;

the method comprising determining failure of the movement-related flight control sensor or the movement-related actuator sensor based on a correlation between an output of the movement-related flight control surface sensor and an output of the movement-related actuator sensor.

14 . The method of claim 13 , further comprising calibrating the movement-related actuator sensor and the movement-related flight control surface sensor against each other at a position within a moveable range of the flight control surface thereby obtaining an actuator reference position and a flight control surface reference position.

15 . The method of claim 13 , further comprising:

determining an effective correlation between a relative movement of the electric actuator and a relative movement of the flight control surface; and

comparing the effective correlation against a predetermined correlation,

wherein the relative movement of the electric actuator is determined based on the output of the movement-related actuator sensor and an actuator reference position;

wherein the relative movement of the flight control surface is determined based on the output of the movement-related flight control surface sensor and a flight control surface reference position; and

wherein the predetermined correlation is a correlation between a movement of the electric actuator and a movement of the flight control surface.

16 . The method of claim 15 , wherein the predetermined correlation is constant over a movable range of the flight control surface.

17 . The method of claim 15 , wherein the predetermined correlation is determined prior to determining the effective correlation.

18 . The method of claim 13 , further comprising:

disabling movement of the flight control surface upon determining failure of one of the movement-related flight control sensor and the movement-related actuator sensor.

19 . The method of claim 13 , further comprising:

at least two movement-related flight control sensors,

wherein upon determining failure of one movement-related flight control sensor, a non-failing movement-related flight control sensor is used to control movement of the flight control surface.

20 . The method of claim 13 , further comprising:

determining that the flight control surface is ready for use by moving the flight control surface to respective end positions of a movable range of the flight control surface.